Mixture control for internal combustion engine



June 19, 1962 H. ElLER 3,040,181

MIXTURE CONTROL FOR INTERNAL COMBUSTION ENGINE Filed Jan. 25, 1961 .INVENTOR. Huqw EILER HTTOKNEKS United States Patent 3,040,181 MIXTURE CONTRQL FORINTERN COMBUSTION ENGINE Harold Eiler, Lapel, Ind., assignor to The Pierce Governor Company, Inc, Anderson, Ind., a corporation of Indiana Filed Jan. 23, 1961, Ser. No. 84,444 14 Claims. (Cl. 290-40) gine operation.

It is an object of the invention to provide a mixture control in the nature of a choke which is' independent of both the cooling system and the exhaust system of the engine with which it is associated. It is a particular object of the invention to provide a mixture control or automatic choke especially adapted for use with 2-cycle outboard engines which are air-cooled or cooled by a non-recirculating fresh water system. It is a further object of the invention to provide'a mixture control which provides a variable choking action which is regulated to parallel the choking needs of the engine during operation under its own power and which also provides increased choking action during starting of the engine. It is a further object of the invention to regulate the choke in response to the running output of an A.C. generator or alternator, in combination with means responsive'to D.C. battery power to increase choking during starting.

In accordance with the invention, the air inflow passage to the, carburetor of the internal combustion engine is provided with an unbalanced choke valve which tends to open in response to air inflow. At'norm al ambient temperature, say 75 F., the choke valve is biased to partially-closed position by a temperature responsive element such area helically wound bimetallic spring, Such element is rotatably mounted, as on a rockshaft, which valve-reaction normally urges in a choke-decreasing direction against :a stop. A solenoidenergized from the battery rotates the rockshaft ina choke-increasing direction during starting, and such rotation acts through the thermal element to move the choke valve in a closing direction. The arrangement is such that at normal start ing temperature the choke valve will be substantially closed when the solenoid is actuated. The solenoid is desirably energized concurrently with the engine. starter so that the choke is moved to full choking position during starting, and is released to a partially open position whenpthe engine starts and the starter'is de-energized.

The bimetalic spring is housed in a heater housing which contains an electric resistance heating element connectedto be heated by running output of'the generator. In the preferred case of. an altenator or A.C. generator which charges the battery through a rectifier, the heater is connected ahead of the rectifier so that it receives generator output but is isolated from the battery by the one-way valving action of the rectifier; The output of the alternator will of course vary with engine speed of p the engine, and this will control the heater output and the temperature of the bimetallic .spring. The bimetallic spring is such that as its temperature rises it relaxes in a choke-decreasing direction, and progressively allows.

the choke valve to open under the influence of'air flow 2 ally operable actuating lever which overrides the automatic control.

Other objects and features of the invention will appear from the following description of a preferred embodiment of the invention.

The accompanying drawing illustrates my invention In such drawing:

FIG. 1 is an elevation, with parts shown in section, of an automatic choke embodying my inventiomin combination with an electrical diagram showing the relationship of the automatic choke and its parts to the electrical system of an internal combustion engine with which it is associated;

FIG. 2 is a section taken on the line 2-2 of FIG; 1;

FIG. 3 is a view similar to FIG. 2, showing in end elevation the housing containing the bimetallic spring, with the housingcover and its supported parts removed but with bimetallic spring shown in end elevation;

FIG. 4 is a section taken on the line 44 of FIG. 1; FIG. 5 is an end elevation taken from the left-hand end of FIG. 1;

FIG. 6 is an end elevation taken from the right-hand end of FIG. 1.

.As indicated in FIG. 1, the'choke mechanism there shown is especially adapted for use with an internal combustion engine having an electrical system in which an A.C. generator or alternator charges the battery through a rectifier. The electrical system shown diagrammatically in FIG. 1 may be considered to be that of an outboard engine. A series of alternator coils 10' are energized by a magnet 12 carried in the flywheel 14 of the engine. The output from such alternator is carried by a pair of wires 15 and 16 to a rectifier 18 having a DC. output terminal 20 connected by awire 22 to the battery 24 of the system. The system may include other conventional elements, such as a voltage regulator not shown. A starter motor 26 is connected to the battery 24 through a relayv switch 28 actuated by a coil 30 connected" to the battery through a starter switch 32. The A.C. output of the alternator is converted by the rectifier to DC. current to charge the battery 24 during running operation of the engine.

The choke mechanism shown in the drawing comprises the body 40 adapted to be mounted against the intake end of a carburetor 38 and defining an air inflow passage42 to the carburetor. A choke shaft 44 is rotatably mounted in the body 40 on an axis extending transversely across the passage 42 and oifset from its center, and such shaft carries a choke valve 46 which in closed position will substantially choke off the passage.

42. The left-hand end of the choke shaft '44.extends into aheater chamber 50 formed by Walls 49 on the body 40, and there carries a choke-actuating crank finger 52, which is desirably covered by a wear sleeve 54. The chamber 50 extends into and is closed bl a hollow cover 56 which carries a fixed central mounting pin 58. A rockshaft sleeve '60 ismounted on such pin 58 bymeans of a sleeve bearing 62 and carries at its end a slotted stud shaft 64 in whichtis mounted a helical-bimetal spring 66. The outer end of this helical spring 66 is turned .out-

\ ward to form a hook 68 which engages the crank finger 52 on the choke shaft 44. The opposite end of the sleeve 60 carries a control arm 70 which normally lies rotated into the carburetor. As the result, the choking action v counterclockwise against a stop 72 fixed in the rear wall of the cover 56. V

The'outer end of the cover 56 forms a housing containing a D.C. solenoid 74 having a core 76 whose forward end 78 extends through the end wall of the cover 56 into the chamber 50. Such forwardend 78 is angularly spaced from the stop 72 and lies in the path of the e operating arm 70 for the rockshaf-t 60. and its bimetal spring 66, and such lever 70 is arcuately notched to em- Fatented June 19, 1962' brace the core-end 78. The relationship is such that the arm 70 forms the armature for the solenoid. Accordingly, when the solenoid is energized, the core 78 attracts the armature lever 70 and rotates such lever 70' clockwise away from its stop 72, to the position shown in dotted lines in FIG. 2. This rotates the sleeve '60 and its bimetallic spring 66 in a clockwise direction in FIGS. 2 and 3, and the spring, in turn, rotates the choke valve clockwise to the closed position shown in dotted lines in FIG. 3. The solenoid 74 is connected by a wire 75 to the starter relay. circuit controlled by the switch 32, so that such solenoid 74 is energized concurrently with the starter 26.

A pair of resistance elements forming heater coils 80 are mounted on an annular disc 82 received between the wall 49 of the chamber 50 and the cover 56'. The two heater coils 80 are interconnected by a mounting eyelet 84 and their outer ends are connected to terminal posts 86 and 88 mounted through the end wall of the cover 56. As indicated in FIGS. 1 and 2, the heater coils 80 are arranged in series and are connected by a wire 81 directly to one wire 16 of the AC. output leads from the alternator -12, so that such heater elements are energized directly by the alternator output at all times when, but only when, the engine is running at A.C. generating speed. The coils are isolated from the battery 24 by the rectifier 18.

--It will be noted that the cover 56 for the heater chamber 50 carries the bimetal spring 66 and its entire operating mechanism, including the rockshaft 60-64 which supports the bimetal spring and the arm 70 which determines the angular position of such parts. To provide for adjusting the action of the choke, the cover 56 is desirably mounted in a manner which permits adjustment of its angular position relative to the choke body 40. To'

92 held by screws 94 taking into three ears 96 on the wall The opposite end of the choke body may carry a manual actuating mechanism as shown in FIGS. 1 and 6. The choke shaft 44 extends outward beyond the end of the body 40 and is provided with a depending pin 98. An actuating lever 100 is loosely mounted on the choke shaft 44 and carries a crank finger 102 which normally lies well beyond the normal range of movement of the pin 98 during the automatic operation of the choke. A screw 104 mounted through an arcuate slot 106 into the end face of the body 40 serves to limit the angular movement of the lever 100. A spring 108 surrounding the screw 106' bears against the lever 100 to retain it in manually adjusted position.

stop '72, and the bimetal spring 66 resiliently holds the choke valve 46 against opening beyond the partially open position shown in FIGS. 3 and 4. When the engine starter'is energized, by manual closing of the starter switch 32 to energize the starter relay switch '28, the closing of the starter; switch 32 also energizes the solenoid ditions. When the engine starts under its own power and the starter switch 32 is opened, this de-energizes the solenoid 74 and allows the armature lever 70 to move counter-clockwise in FIG. 2 to its retracted position against the stop 72. This allows the bimetal spring 66 to rotate counterclockwise back to its position shown in full lines in FIG. 3, and permits the choke valve 46 to move to partially open position. Under running conditions, air infiow through the choke passage '42 tends to open the unbalanced choke valve 46 beyond the partially open position shown, and such further opening is yieldingly opposed by the bimetal spring "66.

'It is characteristic of the conventional alternator or AC. generator 10-42 that it produces some A.C. output. even at idling speeds, and such output is applied across the heater elements 80. At such idling speeds, the engine and its induction system heat up rather slowly, and correspondingly, the alternator output is relatively low and acts to heat the heater elements 80 to only a low temperature. will be dissipated to the choke and carburetor bodies, and the bimetal spring 66 will be only slowly heated; At higher operating speeds, both the alternator output and the consequent heat output of the heater elements 80 will be greater, and the bimetal spring will receive more heat. As the bimetal spring '66 is heated, either slowly or rapidly, it relaxes and winds upon itself to carry its hooked end 68 counter-clockwise in FIG. 3, and this allows the choke valve 46 to move progressively toward fully open position. Therate ofbimetal spring response can of course be varied by selecting different spring characteristics, in accordance with known design practices.

The choke body 40 is mounted against the inlet end of the carburetor 38, in heat transfer relation therewith,

and both the carburetor and the choke mechanism will normally be enclosed within a motor housing. Accordingly, the temperature of the choke body and of the bimetallic spring 66 enclosed within its heater chamber will in part depend both upon the temperature of the induction system and upon the general temperature condition of the engine and the engine compartment.

The position of the choke valve at any particular time will correspondingly depend in part on these temperature conditions, as well as on heat output of the heater 80 controlled by the generator.

When the engine is started under elevated-temperature conditions, the choke valve 46 will initially lie at a more open position than that shown in FIG. 3, because of V is thereby energized, the choke valve 46 will be moved Operation of the choke shown in the drawing is as fol- 74. This pulls the armature leverv clockwise to the dotted line position shown in FIG. 2, against the core 78 of the solenoid, and the lever 70 rotates the rockshaft 60--64 and the bimetal spring 66 clockwise, to move the choke valve 46 to its fully closed position as indicated This produces increased chokin dotted lines in FIG. 3. 7 ing action necessary for star-ting under the assumed contoward closed position through an angle limited by the throw between the fixed stop 72 and thecore' 78 of the solenoid. The actual angular movement of the choke valve will ordinarily be greater than that throw, however, for the choke arm 44 is not coaxial with the rockshaft 60 -64 but is offset upwardly therefrom, and the length of the lever arm (52) on the choke shaft is substantially shorter than the effective lever arm formed on the rockshaft fill-64 by the bimetallic spring 66. Accordingly,

a given rotational movement of the armature'lever 70 i In general, there will be an interchange heat between 1 that provided by the heater energized by the AC;

alternator output and that deriving from the engine and its induction system. In general, the action will produce in the bimetal spring temperature conditions which paral 161 the choking needs of the inductionsystem, withthe Part or even most of the low heat output result that the choke mechanism will automatically provide the amount of choking required under all conditions. v

-I claim as my invention:

1. An automatic choke mechanism for an internal combustion engine, comprising a body forming an inflow passage, a choke valve having a normal position in which it partially closes said passage and being adapted to be urged in an opening direction by inflow through said passage, a bimetal spring operatively connected to bias said choke in a closing direction, a rock shaft on which said spring is mounted, said shaft having a normal stop position to which it is urged by opening movement of the choke valve, electromagnetic means for rotating said shaft in a valve-closing direction during starting of the internal combustion engine, and electro-resistance means for heating said bimetal spring during running operation of the engine, said bimetal spring relaxing with heat to decrease its valve-closing bias.

2. An automatic choke mechanism as set forth in claim 1 with the addition that said body forms a heating chamber and said bimetal spring and said electro-resistance means are mounted in spaced relation therein.

3. An automatic choke mechanism for an internal combustion engine, comprising a body forming an inflow passage, a choke valve having a normal position in which it partially closes said passage and being adapted to be urged in an opening direction by inflow through saidv passage, a bimetal spring operatively connected to bias said choke in a closing direction, a rock shaft on which said spring is mounted, said shaft having a normal stop position to which it is urged by opening movement of the choke valve, electromagnetic means for rotating said shaft through a limited angle in a valve-closing direction during starting of the internal combustion engine, and electro-resistance means for heating said bimetal spring during running operation of the engine, said bimetal spring relaxing with heat to decrease its valve-closing bias.

4. An automatic choke as set forth in claim 3 with the addition that said rock shaft is offset from the axis of rotation of said choke valve, and said choke is connected to said bimetal spring by a choke-actuating lever arm which is shorter than the effective lever arm formed by said spring between the rock shaft and choke-actuating lever arm. a

5. An automatic choke mechanism for an internal combustion engine, comprisinga body forming an inflow passage, a choke valve mounted on a choke shaft extending across said passage and rotatable in valve-opening and valve-closing directions, an operating crank on said shaft, a bimetal spring engaging said crank in a direction to oppose valve-opening movement of said choke shaft, a rock shaft supporting said spring, stop means supporting said rock shaft against movement beyond a predetermined position in its valve-opening direction of movement, an armature lever on said shaft, electromagnetic means for rotating said lever and rock shaft in a valve-closing direction to increase the choking action of said choke valve, and electro-resistance heating means for heating said bimetal spring to relax the same in a direction to permit valve-opening movement of said choke shaft to decrease the choking action thereof.

6. An automatic choke mechanism as set forth in claim 5, in combination with an internal combustion engine having an AC. generator connected to charge a battery through a rectifier, switch means connected for energizing said electromagnetic means from said battery, and

means for energizing said electro-resistance means directly from said generator at a point isolated from said lying beyond the range of movement of said arm and being movable upon manual rotation of said lever into choke actuating engagement with said arm.

8. An automatic choke mechanism for an internal combustion engine, comprising a choke valve movable between choking and non-choking positions, a choke shaft controlling the position of said valve, a rock shaft in substantially end-to-end relation with said choke shaft, a crank arm on one of said shafts, a bimetal element on the other of said shafts and operatively engaging the crank arm in a direction to oppose choke-decreasing movement of the choke shaft, stop means limiting angular movement of said rock shaft in choke-decreasing direction, and electromagnetic means for rotating said. rock shaft in choke-increasing direction, and electro-resistance heater'means" for heating said bimetal element, said bimetal being constructed and arranged to respond to increased temperature by relaxing in a choke-decreasin direction.

9. An automatic choke mechanism, for an internal combustion engine, comprising a body forming an inflow pas-,

sage, a choke valve mounted in said passage on a transverse. choke shaft, walls on said body forming a chamher into which said choke shaft extends, a rock shaft having an end portion lying in said chamber, a bimetal element on one of said shafts and an arm on the other and interconnecting the same within said chamber to control valve-opening movement of the choke shaft, stop means limiting movement of said rock shaft in a valveopening direction, means to rotate said rock shaft in a valve-closing direction for increasing the choking action of said choke valve, said bimetal element being operative when heated to relax in a direction to permit valve- -opening movement of the choke shaft to decrease the choking action of said choke valve, and electro-resistance means mounted in said chamber for heating said bimetal to cause such relaxing action.

10. An automatic choke mechanism as set forth in claim 9 in which said chamber is closed by a cover removable from said body, and said rock shaft, stop means, and rock shaft rotating means are mounted in said cover;

11. An automatic choke mechanism as set forth in claim 9 in which said chamber is closed by a cover separable from said body at a position intermediate the length of the chamber, and said electro-resistance means is mounted a having an electrical system including a battery and an alternator connected to charge the battery through a rectifier, automatic choke means comprising a choke valve movable between choking and non-choking positions, a choke shaft controlling the position of said valve, a bimetal element operatively connected to oppose choke-de creasing movement of said shaft, movable means normally supporting said bimetal element in a predetermined stop position, said bimetal element being constructed and arranged to respond to increased temperature by relaxing in the direction of choke-decreasing movement of said choke shaft, electro-magnetic means connected for energization from said battery to move said movable means and bimetal element in a choke-increasing direction, and electro-resistance heating meansconnected for energization direct from said alternator ahead of said rectifier for heating said bimetal element to relax the same in choke decreasing direction.

13. The combination set forth in claim 12. with the addition of a switch controlling a starter for said engine, and means connecting said electro-magnetic means for ener-gization concurrently with the starter.

' 14. In combination with an internal combustion engine having an electrical system including a battery and a charging generator connected to charge the battery through a valve device permitting current flow from the generator to the battery and preventing reverse flow, automatic choke means comprising a choke valve movable between choking and non-choking positions, a choke shaft I said bimetal element being constructed and arranged to respond to increased temperature by relaxing in the direction of choke-decreasing movement of said choke shaft,

electromagnetic means connected for energization from 10 8 7 said battery to move said movable means and bimetal element in a choke-increasing direction, and electro res'ist-a-nce heating means connected for ener-gization direct from said generator ahead of said valve device for heating said himetal element to relax the samein choke-decreasing directions in response to generator energizing operation of said engine. 1

No references cited. 

